The present invention is directed to a disk based backup storage system that can be seamlessly integrated with a tape backup system or the like and, more specifically, to a system and method of exporting a virtual tape from a virtual library.
Backing up computer data, restoring computer data, securing computer data and managing computer data storage (collectively referred to as data protection) requires complex and disparate technical and operational solutions. Data protection is the single most expensive storage administrative task.
One data protection strategy is to use a redundant array of independent disks (RAID) and disk mirroring technology to protect data. Unfortunately, disk mirroring only prevents data loss in the event of a hardware or power failure. Mirroring does not protect data from human error, such as the accidental deletion of portions of a document. On a disk mirrored system, once data has been deleted from the primary disk, the data is automatically deleted from the mirrored disk and not retrievable.
To address the problem of human error and computer viral damage, backup systems have been designed that are file-based and track files for many generations. One typical form of data protection backup uses physical tapes to store data in tape libraries. Physical tape backup libraries provide the ability to restore current and historical data and to recover from a variety of forms of data loss.
Referring to FIG. 3, a typical physical tape library 12 is shown. Tape cartridge slots 14 provide storage slots for physical tapes 13. This physical tape library has 40 slots 14 with some of the slots 14 shown containing physical tapes 13. Four tape drives 15 are shown along the bottom of the physical tape library 12 that can be used for reading from, and writing to, the physical tapes 13. Barcode labels 17 are typically used with physical tapes 13 to facilitate automated tape handling and tracking by the data protection application. The physical tapes 13 typically also have a human readable version of the information coded in the barcode to allow manual selection and identification of the physical tapes 13.
A typical physical tape library 12 includes a built in barcode reader which is used to read the barcode labels 17 on the physical tapes 13. Typical data protection applications keep track of data that is backed up on tape 13 by associating the data with a tape 13 having a particular barcode. By including in a barcode reader, the physical tape library can identify a particular physical tape 13.
Physical tape libraries 12 preferably include an entry/exit port 19. The entry/exit port 19 (shown in the upper left hand side of FIG. 3) provides a pathway for tapes 13 to be automatically moved into and out of the physical tape library 12. A tape 13 in the entry/exit port can be accessed by a human operator while the rest of the tapes 13 are secured within the physical library housing. Robotic mechanisms are used to move a tape 13 between the slot 14 and the entry/exit port 19.
To automate the mounting and unmounting of tapes into tape backup drives, many organizations use a robotically controlled tape library. Actual usage of individual tape media is generally very infrequent. Backup jobs typically run at night during a period called the “backup window”. Typically, organizations use tape rotation schemes whereby the organization writes to daily tapes, weekly tapes and monthly tapes. Many of the tapes are sent off-site after being written to, and are not accessed again until either computer data must be restored or the computer data on the backup tape has expired (usually after some number of weeks, months or even years). Additionally, adding to the size of a tape library can be a complicated matter requiring the integration of additional tape libraries into the data protection application.
One significant problem with physical tape libraries that are used with mainframe systems, is the unused portion of each physical tape that typically remains after a tape has been used to store data. To overcome this problem, virtual tape libraries have been developed that act as an intermediary between the data generating network and the physical tape library. These virtual libraries are used to accumulate data in virtual tapes until enough data is collected to fill a physical tape by placing more than one virtual tape on a single physical tape. This process is known as stacking. These virtual libraries record the data onto the physical tape libraries using a proprietary format.
Three significant drawbacks with the above described virtual libraries are that when virtual tapes are copied onto physical tapes, because they are written in a proprietary stacked format, they can only be restored by using the proprietary virtual tape system. This introduces a long-term problem because an organization is tied to maintaining the propriety virtual library in order to access their historical data. Additionally, since multiple virtual tapes are stacked onto one physical tape, exporting the physical tape results in removal of multiple virtual tapes, even though the user may have only intended to remove a single virtual tape. Finally, tape stacking makes using a data protection application complicated, since the virtual tape to which the application wrote to different from the resultant physical tape. Therefore, this adds additional steps into the tape management process.
Clearly, what is needed is a data protection system that: handles a virtual tape in an equivalent manner to a physical tape; uses non-proprietary coding and formatting when creating physical tapes; can export a single virtual tape onto a physical data storage device without also copying unselected virtual tapes onto the device; and can be seamlessly integrated with an existing data protection application so that the data tracking algorithms on which operators have been trained, and have developed institutional knowledge, do not need to be changed.